Datasets:
karthikmns
/
eval_testing_mns

Dataset card Data Studio Files
xet
 Community
1
SC
stringlengths
1
129
⌀
studied the way in which plants form oxygen. In 1779, he noticed that it
happened only in the presence of light. In an experiment with the aquatic
null
null
null
null
AN
plant, Hydrilla, he observed that in bright sunlight, small bubbles formed
around the green parts while in the dark they did not form. He also found
that the gas present in the bubbles was oxygen.
It was further confirmed when Engelman in the early 20th century
ingeniously detected the point of maximum rate of photosynthesis. He
null
null
null
null
NG
used a strand of algae and exposed it to different colours of light (the
colours that we see in a rainbow) Then he used oxygen sensitive bacteria
and found that they crowd around areas illuminated with red and blue rays
of light. This led to more studies on effect of light on photosynthesis, the
role of different coloured compounds called pigments in plants and the
utilization of light energy.
LA
Lab Activity
Oxygen is produced during photosynthesis in the presence of light
TE
null
Arrange the apparatus as shown in the figure. Make
two identical sets. oxygen
null
Place some water plant like Elodea or Hydrilla in bubbles
a short stemmed funnel and keep it in a beaker.
Then pour the water in the beaker.
T
null
null
test tube
Invert a test-tube full of water over the stem of the
funnel. Ensure that the level of water in the beaker beaker
ER
null
null
null
null
is above the level of stem of the inverted funnel. water
Place one apparatus in the sun and the other in the
funnel
dark for at least 2-3 hours. You would see that in place
of water there is air that fills in the set up kept in sun. It Hydrilla plant
null
is actually a gas that will be collected in the test-tube.
SC
null
null
null
null
Observe the other set up kept in dark. Is there any fig-5: Hydrilla experiment
difference in the amount of gas collected?
Test the gas in the test-tube by inserting a glowing match stick or
incense stick which would burst into flames. This shows the presence of
oxygen.
What precautions do you need while removing test tube from the beaker.
Discuss with your teacher.
Free distribution by T.S. Government 2019-20 7
Activity-3
Sunlight is necessary to form starch in green plants
null
null
null
null
A
AN
NG
fig-6: Black paper experiment
null
Take a potted plant with destarched leaves. Remember the process of
destraching leaves mentioned in activity-1.
Cover one of its leaves with black paper on which a design is cut. Fix the
LA
paper on the leaf in such a manner that light does not enter the dark part.
Place this potted plant in sun light.
After few hours of exposure to bright sunlight, test the leaf which is
covered by black paper for the presence of starch.
TE
null
Which part of the leaf turns blue black? What about the remaining
part?
Observe the colour of leaf stained with iodine. Can you tell why it
is stained differently?
It will be observed that only the parts of the leaf, which could get light
T
null
null
null
through the cut out design, turns blue-black showing the presence of
starch.
ER
null
null